1. Field of the Invention
The present invention relates to an organic thin-film transistor and a method for manufacturing the same, and particularly, to a method in which a polymer strip is formed on an organic thin-film transistor to define a channel length and then an electrode of the organic thin-film transistor is formed by screen printing to provide a better pattern for the electrode. By using this method, an organic thin-film transistor top-contact/bottom-gate structure can be manufactured.
2. Description of the Related Art
Displays that are thin, power saving, radiationless and full color have become the main stream of the market and are widely used as display devices in various products such as portable personal computers, television sets, electronic handheld games, electronic dictionaries, calculators, car navigation systems and cellular phones. An organic thin-film transistor (OTFT) made of organic materials is developed for applications in electronic products to accelerate the realization of flexible electronic products, such as displays.
According to the OTFT technology, organic materials are provided on a substrate by printing to form a thin-film transistor. Operation of the printing process is relatively simple and it is thus expected that the manufacturing cost thereof will be substantially reduced, compared to the expensive photolithography process. However, the channel length obtained by the present printing process is about several tens of micrometers, which is far from the size of submicrometer range achieved in semiconductor process, and consequently these two technologies are adapted to different applications. To reduce the channel length, in the present invention, a polymer strip is provided to define a channel length on an organic semiconductor layer, and then a polymer organic electrode of the organic thin-film transistor is formed by using screen printing. Therefore, a finer pattern of the polymer organic electrode can be obtained with reduced channel length, and thereby the mobility of electrons and holes is enhanced.
In a process of manufacturing a bottom-contact organic thin-film transistor proposed by Seiki Epson in 2003, a polymer which is not dissolved with an organic electrode is provided to define a channel length, and then the organic electrode is formed by inkjet printing. This method for manufacturing an organic thin-film transistor consumes more time and results in imperfectly straight edges in the electrode.